| Primary liver carcinoma (PLC) is one of the most common seen digestive tract malignancies in the word, nighty percent of them are hepatocellular carcinoma (HCC). According to information statistics, eighty percent of the HCC patients are in developing country, such as Southeast Asia, and the central and western Africa.In china, HCC is the digestive tract malignancies which jeopardize people health. Each year, there are nearly 360,000 morbidity cases and 350,000 mortality cases. In Guangxi, the HCC morbidity rate is high. Epidemiologic studies show that aflatoxin diet exposure and hepatic C vivus infection are two major pathogenic factors for HCC. Previous studies considered diet exposure to aflatoxin are the major road. In past ten years, primary prevention strategies against aflatoxin diet exposure have been draw great public attention, this may low down the incidence of HCC theoretically, however, according to the related studies and our clinical observations, the incidence of HCC remains high, and raised year by year, especially in certain populations (such as sugar refinery workers, paper mill workers and poultry farm workers), but the dietary habits and HB V infective rate of these workers are not different from the rest of the population. Our preliminary study also showed that some of them were found detectable level of serum AFB1 or AFB1-ALB, and this was accordance to the abroad. Thus, we considered that there might be other AFB1 exposure pathways contributing to the high incidence of HCC.According to our field work, these people have a common characteristic: exposure to occupational dust in work, such as bagasse dust and grain dust. As we know that, Guangxi province locate in subtropical area, and period with the mild and wet weather is long, which is easily for mold reproduction. Thus, we suspect that AFB1 could enter body by being inhaled, and it may be associated with the HCC.In order to confirm this, we choose a big sugar refinery, analyzed the 30 years HCC morbidity in dust exposure group and other group, detected the concentration of AFB1 in certain place (such as sugar refinery) in epidemiologic study, We also collected the blood samples from dust exposure group and other group, and compared the concentration of AFB1-ALB between these two groups of people, investigate the potential association-ship between AFB1 airway exposure and HCC. We used the AFB1 airway exposure animal model to investigate the association between AFB1 airway exposure and serum concentration of AFB1-ALB, and demonstrated that AFB1 could enter body by inhaling contaminated dust. We dynamic investigated the alteration of hepatic histology, P53 expression, P21 expression in AFB1 airway exposure animals, and also investigated the effect of AFB1 airway exposure on liver. This study may help people to realize the association between different aflatoxin exposure role and HCC, and provided theoretical basis and experimental evidence for HCC precaution.This study included three sections:Section I:Epidemiologic study and the AFB1-ALB in related populationObjective:to investigate the association between bagasse dust exposure and cancer morbidity, detect the AFB1 contaminated in high concentration dust workplace (such as sugar refinery), and to investigate the effect of AFB1 airway exposure on serum concentration of AFB1-ALB level in related population.Methods:the retrospective analysis method was used, and a big sugar refinery was chose. Information of workers who worked in sugar refinery between 1984 and 2013 were collected, thirty years malignancy mortality rate was counted in dust exposure population and other population air samples in high concentration dust workplace and other workplace. Bagasse dust samples were collected, AFB1 was tested by using ELISA, and it was compared with the mortality rate in local. The SMR was counted. According to the inclusion criteria and exclusion criteria, one hundred and eighty-one workers (Group A) who worked in high concentration dust place such as sugarcane bagasse warehouse, presser workshop and paper production workshop, and 203 workers who worked in other workplace were selected, serum concentration of AFB1-ALB was tested by using ELISA. Fifty rice samples were collected from relate group’s family by using random sampling method.Results:A total of 119852.9 person-years were observed. And five thousand seven hundred and ninety-one workers who worked in sugar refinery between 1984 and 2013 were followed up. Between January 1984 and December 2013, there were 835 patient (included retire workers) in this factory. Among them, there were 330 cancer patients (39.52%). In dust exposure group, morbidity of the malignant tumors rank first in spectrum, and the second and third were respiratory disease and cardiovascular disease, respectively; in another group, the top three in morbidity spectrum were cardiovascular disease, malignant tumors, and respiratory disease, respectively. In dust exposure group, the relative risk (RR) for HCC and lung cancer raised 4.3 fold and 2.63 fold comparing to another group, however, the RR for other malignancy did not raise significantly. ELISA analysis showed that AFB1 was positive in 102 out of 181 group A workers, the concentration of which was 38.51±44.80 pg/ml albumin; in another group workers, AFB1 was positive in 12 out of 203, and the concentration of which was 15.58±6.42 pg/ml. There was significance different between two groups of workers. AFB1 was negative in 50 rice samples. Section II confirm the association between AFB1 airway exposure and serum concentration of AFB1-ALB level by using New Zealand rabbits AFB1 airway exposure animal modelObjects:To investigate effect of AFB1 airway exposure on rabbits serum AFB1-ALB level and hepatic function parameters ALT, AST, ALP, and TP value.Methods:by using random sampling method, Sixty New Zealand rabbits were selected and were divided into three groups according to the exposure level: high exposure group (group A, N= 20), moderate exposure group (group B, N= 20), and low exposure group (group C, N=20). AFB1 solution was drop into the rabbits airway by using trachea cannula. The exposure level for group A, group B and group C rabbits were 75ug/Kg,50ug/Kg, and 25ug/Kg, respectively. Rabbits serum AFB1-ALB level, hepatic function parameters ALT, AST, ALP, and TP value in day 1, day 3, day 7 and day 21 were tested.Results:Four rabbits died during experiment period, including 3 rabbits in group A and 1 in group B. In day 1, AFB1-ALB was positive in eight out of the seventeen rabbits (47.06%) in group A, and the mean value of them was 3.35±1.86 (1.3-6.8) pg/ml; In day 3, the number of rabbits with positive serum AFB1-ALB level rise to ten (58.82%). In day 7 the number was eleven (64.71%), but decline to three (17.64%) in day 21. In group B, the serum AFB1-ALB was positive in three (15.79%) of them in day 1, the concentration of which was 1.97±0.95 (0.9-2.7) pg/ml; In day 3 and day 7 the number was five (26.32%), however, it decline to two (10.53%) in day 21. In group C, serum AFB1-ALB was negative in all rabbits. Hepatic function parameters ALT, AST, ALP, and TP value continuous elevated in serum AFB1-ALB positive rabbits, but did not elevated in serum AFB1-ALB negative rabbits. Hepatic function parameters were analyzed. Comparing to the controls (serum samples which collected from rabbits before exposure to AFB1), the value of ALT and ALP in group A in day 3, the value of ALT, AST, ALP and TP in group A and group B in day 3 and day 7, the value of TP in group A in day 21 elevated significantly. Correlation analysis showed that there was a correlation between the value of ALT and AST and serum AFB1-ALB level in day 7 (P<0.05), however, no correlation was found between the value of ALP and TP and serum AFB1-ALB level (P>0.05)Part III To establish AFB1 airway exposure animal model tree shrew and to futher realized histomorphology change and alteration of P53 expression, P21 expression in liver tissue samplesObjects:To investigate the effect of airway exposure to different level of AFB1 on P53 status, P21 status and histomorphology in tree shrew liver tissue samples.Methods:Eighty tree shrews were selected and were divided into three groups:group A (Blank group), and group B (Airway exposure group). Group B Tree shrews were exposure to AFB1 in 200ug/Kg/D, six times per week. Blood samples and liver tissue samples were collected according to the scheme. Histomorphology, P53 expression, P21 expression and histomorphology were tested continuous.Results:this part began in September 11,2013, and end in January 28, 2015, lasting 504 days (72 weeks). Sever tree shrews in group B died during this periods. At the end of experiment, none tree shrew in group A with positive serum AFB1-ALB level was found, the hepatic histological change was not found, and the P53, P21 abnormal expression were not found in any tree shrews. In group B, eight of them were found that the serum AFB1-ALB level elevated in first week, and in the third weeks, serum AFB1-ALB was positive in all of the tree shrews. In group A tree shrews, none of them were found hepatic histological change. In group B tree shrews, the first pathological examination in week 33 showed that there was a slight inflammatory response in tree shrews liver tissue samples, the portal tract was infiltrated by inflammatory cell, spotty necrosis was found in liver cells, and focal necrosis and piecel necrosis were also occasionally found. In week 43, Kuffer cells proliferation cound be found, inflammatory cells were seem, and the liver cells with vacuolar degeneration and hyaline degeneration could be seem. In 72th weeks, Liver structure disorderly was found in tissue samples, acidophilic degeneration and heavy hydropic degeneration could be found.Conclusions:1, It is certain that AFB1 could enter the body by airway exposure.2, serum AFB1-ALB elevation is associated with exposure level and exposure time.3, Continuous exposure to airway AFB1 can results in hepatic disfunction in serum AFB1-ALB positive animals.4, It needs further confirm that whether there is a correlation between AFB1 airway exposure and morbidity of HCC. |
PDF Full Text Request